From: Miroslav Benes <[email protected]> The tiny RCU CPU stall detection depends on *rcp->curtail not being NULL. It is however a tail pointer and thus NULL by definition. Instead we should check rcp->rcucblist for the presence of pending callbacks which need to be processed. With this fix INFO about the stall is printed and jiffies_stall (jiffies at next stall) correctly updated.
Note that the check for pending callback is necessary to avoid spurious warnings if there are no pendings callbacks. Signed-off-by: Miroslav Benes <[email protected]> [ paulmck: Fused identical "if" statements, ported to -rcu. ] Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tiny_plugin.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h index 858c56569127..80f908afe348 100644 --- a/kernel/rcu/tiny_plugin.h +++ b/kernel/rcu/tiny_plugin.h @@ -145,17 +145,16 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp) rcp->ticks_this_gp++; j = jiffies; js = ACCESS_ONCE(rcp->jiffies_stall); - if (*rcp->curtail && ULONG_CMP_GE(j, js)) { + if (rcp->rcucblist && ULONG_CMP_GE(j, js)) { pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n", rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting, jiffies - rcp->gp_start, rcp->qlen); dump_stack(); - } - if (*rcp->curtail && ULONG_CMP_GE(j, js)) ACCESS_ONCE(rcp->jiffies_stall) = jiffies + 3 * rcu_jiffies_till_stall_check() + 3; - else if (ULONG_CMP_GE(j, js)) + } else if (ULONG_CMP_GE(j, js)) { ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check(); + } } static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp) -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
